PROJECT SUMMARY Background. In Nigeria, men who have sex with men (MSM) are largely understudied and have elevated risk for substance abuse, mental health problems, and HIV infection. While research on MSM in Africa remains limited, recent work has documented high prevalence of psychosocial problems, such as depression and suicidal ideation, among African MSM1-5. Additionally, Nigerian MSM are confronted with social stigma, homophobia, and discrimination, and many continue to conceal their same-sex identity and sexual partnerships, especially after the passage of the Same-Sex Marriage Prohibition Act in 2014. This proposal builds on our formative work with MSM in Nigeria, which revealed a majority exhibited depressive symptoms and were problem drinkers. This formative qualitative work, however, enrolled a relative small sample (N=30). In order to be effective, future substance abuse treatment interventions HIV prevention for this at risk, marginalized group need to be based on a better understanding of the co-occurrence of psychosocial risk factors (minority stress and mental health issues) and their relationship to drug and alcohol abuse and HIV risk behaviors. Overview of project. We propose to conduct a multi-state, cross-sectional quantitative behavioral research study with 220 Nigerian MSM to explore co-occurrence of psychosocial problems and association with HIV-related sexual risk. We will also explore possible synergistic effects of multiple psychosocial problems on HIV risk and the possibility of a pathway from minority stress to HIV sexual risk through psychosocial problems. In Phase 1, we will recruit a diverse sample (N=20) of Nigerian MSM from four different states (Lagos, Abuja, Kano and Plateau) to complete semi-structured interviews, specifically iterative cognitive testing of cultural relevancy, understanding, and acceptability, and understanding of validated scales of minority stress and psychosocial problems. In Phase 2, Nigerian MSM (N=200) will complete a comprehensive behavioral assessment containing measures on demographics, minority stress, substance use, mental health, and sexual risk assessment. As a whole, these results will serve to inform a culturally appropriate, drug/alcohol abuse treatment/prevention and HIV prevention intervention for this high-risk subpopulation of MSM.